Impression Share

Impression Share is the percentage of impressions your ads received compared to the total impressions they were eligible to receive. It indicates how much of your potential market you’re actually reaching. If your Impression Share is 60%, you’re missing 40% of possible ad appearances.

Google breaks this down further: Search Lost IS (Budget) shows impressions lost because your daily budget ran out, while Search Lost IS (Rank) shows impressions lost because your Ad Rank wasn’t high enough to compete. Monitoring Impression Share helps diagnose performance problems, for example sudden drops often indicate increased competition, Quality Score declines, or budget constraints. For competitive industries, achieving high Impression Share requires substantial budgets.

Example: A criminal defense attorney notices their Impression Share dropped from 75% to 45% over two months. Checking the breakdown reveals they’re losing 30% to rank, suggesting a competitor increased bids or their Quality Score declined.